The present invention relates to a process for the production of optically active cyanohydrins by reaction of aldehydes with hydrocyanic acid in the presence of D-oxynitrilase.
Optically active cyanohydrins serve primarily as intermediate products for the production of corresponding optically active 2-hydroxycarboxylic acids. Optically active 2-hydroxycarboxylic acids obtained thereby in turn are esterified to a large extent with chrysammic acid and then can be used in the commercially important pyrethroid insecticides. Optically active mandelic acid is then frequently used for the dissociation of racemic compounds of basic (alkaline) compositions.
It is already known from Biochemische Zeitschrfit 346, 301-321 (1966) to produce optically active cyanohydrins by reaction of aldehydes with hydrocyanic acid in the presence of D-oxynitrilase (E.C.4.1.2.10) in a 0.05M 50% alcoholic acetate buffer at a pH of 5.4.
German Pat. No. 1 300 111 of the same authors discloses that it is known to undertake this reaction in a pure aqueous 0.05M acetate buffer at a pH of 5.4, to use the D-oxynitrilase in the form of its combination with an organic ion exchanger which is insoluble in the reaction mixture, such as ECTEOLA-cellulose (reaction product of epichlorohydrin, triethanolamine and sodium cellulose) or DEAE-cellulose (diethyl aminoethyl-cellulose).
In the known process, which is carried out in a reaction medium with a high water content, numerous aldehydes can be converted into more or less high chemical yields and into more or less high optical yields of optically active cyanohydrins. Table 2 of on parge 310 of the above "Biochemische Zeitschrift 346" seems to infer, however, that numerous other aldehydes cannot be converted into optically active cyanohydrins.